When the famous disastrous Paris Agreement was signed in 2015 to regulate emissions into the atmosphere, scientists set two critical parameters for assessing its implementation. The first is the achievement of an increase in the average global temperature by 2100 by no more than 2 ° above the pre-industrial level. Above + 2 ° means an imminent catastrophe, therefore, in fact, people should strive to keep the temperature rise much lower, by only 1.5 °. But in reality we don't have that much time.
All people need to do is simply to reduce emissions into the atmosphere everywhere, but you cannot take and close factories and thermal power plants without bringing down the economy. Countries are developing and implementing plans for a phased transition to renewable sources, and scientists are assessing the effectiveness of these initiatives on a global scale. With a rough estimate, there are only four scenarios for the development of the situation, all of them set a point of no return, after which it becomes useless to fuss and the planet will definitely overheat above the risk level.
The first scenario is pessimistic, according to it, the reduction of emissions with the parallel commissioning of "green energy" will not exceed 2% per year on a planetary scale. If so, then we will not be able to keep the temperature rise by +1, 5 ° by 2100th. But if suddenly all countries of the world in a single burst provide a 5% reduction in emissions, then the point of no return shifts to 2027. The chance is scanty, but it is there.
The third scenario is a 2% reduction in emissions, but agreement on a total temperature rise of 2 °. According to it, the point of no return will be in 2035. And if we take the extreme scenario, then with a 5% reduction in emissions and a border of + 2 °, we have time until 2045 to influence the climate. The authors of the calculations clarify that their accuracy is no more than 67%, plus it is necessary to take into account the influence of technologies for removing greenhouse gases from the atmosphere, if any major power decides to do this seriously. The main goal of all this simulation is directly voiced: to scare politicians and force them to do at least something in order to save humanity from the wrath of the planet.